Everton boss Frank Lampard admits Asmir Begovic has picked up an ankle strain.
Lampard was speaking after their preseason defeat to Arsenal in Baltimore.
Lampard said: “We all know what a good season Jordan (Pickford) had last year… for me it is a godsend to have a keeper at that level and playing so well, he is critical to results.
“And he is a leader in the group, maturing all the time, so [the captaincy was] absolutely deserved.
“Asmir twisted his ankle in training making a save.
“He' gone for scan and we'll know the results tomorrow [Sunday].
“Hopefully it is a minor one that is weeks not months [out of action]."